Telephone-exchange system



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Aug. 25, 1925. 1,550,997

' s. B. WILLIAMS. JR

TELEPHONE EXCHANGE SYSTEM Filed June 18, 1920 3 Sheets-Sheet 1 /nvenf0rSamue/ B. Wi/l/kzms Jr y Affiz Aug. 25, ,1925.

S. B. WILLIAMS. JR

TELEPHONE EXCHANGE SYSTEM Filed June 1 1920 3 Sheets-Sheet 2 W if;i'EEJEPHUi W.

. lnvenfar; Samuel 13. Wi///ams JI."

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Patented Aug. 25, 1925.

UNITED STATES PATENT OFFICE.

SAMUEL B. WILLIAMS, JR., O'F BROOKLYN, NEW YORK, ASSIGNOB TO WESTERNELEC- TRIO COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OFNEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed June 18, 1920. Serial No. 389,819.

To all whom it may concern:

Be it known that I, SAMUEL B. WVILLrA us, J r., a citizen of the UnitedStates, resldmg at Brooklyn, in the county of Kings, State of New York,have invented certain new and useful Improvements in Telephone-ExchangeSystems, of which the following is a full, clear, concise, and exactdescription.

This invention relates to telephone exchange systems and particularly tocircuit arrangements for use at a private branch exchange when such anexchange is employed in connection with a central oilice, either of themanual or automatic type.

An object of the invention is to provide novel and improved means forenabling a subscriber of the private branch exchange to extend his lineat will, either to the attendant of the private branch exchange, or overan idle one of a plurality of trunks I leading to the central ofiice,the latter conncction being effected without the aid of the operator.

A feature of the invention consists in the provision of a set of relaysindividual to each subscribers line of the private branch exchange,which respond to the initiation of a call and the sending of a certainpredetermined number of impulses from an impulse sender at the callingstation to actuate a calling signal at the private branch exchangeattendants position, and to the initiation of a call, and the sending ofanother predetermined number of impulses from an impulse sender at thecalling station to automatically extend the calling line over an idleone of a plurality of trunks leading to the central oflice.

The inventive idea involved is capable of receiving a variety ofexpressions, one of which, for the purpose of illustrating theinvention, is shown in the accompanying drawings; but it is to beexpressly understood that said drawings are employed only for thepurpose of facilitating the description of the invention as a whole, andnot to define the limits thereof, reference being had to the appendedclaims for this purpose.

In the drawings, Figures 1, 2, 3 and 4: with Figure 2 arranged beneathFigure 1 and Figure 3 to the right of Figure 1, illustratediagrammatically, the circuits em ployed in carrying out the invention.

cordless switchboard as desired with a sufii-' cient number of trunklines extending from the switchboard to the central office to care forthe tratfic. Each subscribers line has an impulse sender associatedtherewith, and extends through key contacts to a set of re laysindividual thereto. The system is so arranged that upon removing thereceiver and actuating the dial to send two impulses, certain relays ofthe set will operate and actuate the line signal at the attendantsposition, whereas removing the receiver and actuating the dial to sendthree impulses, additional relays of the set, individual to the callingline, will be actuated to extend the calling line to an idle trunkleading to the central oflice.

Each subscribers line is provided with a row of connecting keys and aringing key. \Vhen the line signal is actuated, the attendant noting it,will actuate a connecting key and her listening key, and upon learningthe number desired by the calling subscriber, will actuate the ringingkey of the desired line and then the connecting key associated with thatline in the same row with that of the calling subscriber. The lines arethen connected for conversation.

Should the calling subscriber desire the attendant to call a subscriberat the central otiice, the attendant will actuate a key individual to atrunk line leading to the central otiice and after having obtained aconnection with the central ofiice, actuate a connecting key associatedwith the trunk in the same row with an actuated key of the callingsubscriber.

If the calling subscriber of the private branch exchange desires acentral oiiice connection without the aid of the operator, he will dialthe digit 3. The line signal will not light, but his line will beautomatically extended to an idle outgoing trunk. The trunk circuits aredesigned for either incoming calls from the central otfice or outgoingcalls thereto. If a trunk is taken for use in either direction, a busysignal is dis played at the attendants position. If all trunks are busy,and a subscriber in the private branch exchange dials digit 3 to extendhis line to an idle trunk, his line will be automatically extended tothe operators position to light a signal thereat. The operator may theninform him that all trunks are busy.

The trunk lines E and D may terminate in a jack such as 107 at a manualswitchboard as shown in Figure 3, or in a non-numerical switch such as Fat an automatic exchange, as diagrammatically represented in Figure 4.

It is believed that the invention will now be fully understood from thefollowing detailed description of the operation in establishing thevarious connections. Let it first be assumed that the subscriber atsubstation A desires to converse with another subscriber within theprivate branch exchange. Upon the removal of the receiver from its.switchhook, supervisory relay 24 and line relay 20 individual to thesubscribers line are energized over a circuit extending from groundedbattery, left-hand winding of relay 20, back contact and outer lefthandarmature of relay 21, conductor 80, lower and upper left-hand normalcontacts of connecting key 22, lower and upper lefthand normal contactsof key 23, through the substation loop, upper right-hand normal contactsof key 23, Winding of supervisory relay 24, lower right-hand normalcontacts of key 23, upper and lower right-hand normal contacts of key22, conductor 81, inner left-hand armature and back contact of relay 21to ground. Line relay 20 is differentially wound. Suiiicient currentdoes not flow through the righthand winding of relay 20, however, aslong as the loop is closed, to deenergize relay 20, due to the shortcircuit for this winding at the inner armature and back contact of relay21. WVhen the subscribers loop is interrupted the right-hand winding ofrelay 20 serves to quickly deenergize said relay. Line relay 20 inoperating completes a circuit at its left-hand armature and frontcontact for slow-to-release relay 25. Relay 25 in operating completes acircuit at its upper armature and front contact for line busy signal 30.

The subscriber at substation A may then operate his impulse sendingdevice S to send two impulses. Upon the first interruption of thesubstation loop, relay 20 deenergizes, thereby completing a circuit forslowtorelease relay 28, extending from ground, left-hand armature andback contact of relay 20, lower armature and front contact ofslow-to-release relay 25, right-hand armature and back contact of relay26, lower armature and back contact of relay 27, upper normal contactsand winding of relay 28 to grounded battery. Relay 28 operates and locksup through its upper alternate c011- tacts to ground at the left-handarmature and back contact of relay 20. Relay 27 does not operate atthistime, since the upper Winding, through which current flows in parallelwith the winding of relay 28 at the time of the first interruption ofthe calling sub-station loop, is non-inductive. As soon as relay 28operates, and relay 2O attracts its armature at the end of the firstinterruption of the line loop, relay 27 operates over a circuitextending from grounded battery, through the non-inductive winding ofrelay 27, the lower inductive winding of relay 27, front contact andlower armature of relay 28, right-hand armature and back contact ofrelay 29, inner right-hand normal contacts of relay 21 and front contactand upper armature of relay 25 to ground. Relays 25 and 28 being of theslow-to-release type, do not release their armatures during the sendingof a series of impulses.

Upon the second interruption of the line circuit, relay 31 operates overa circuit extending from ground, left-hand armature and back contact ofrelay 20, lower armature and front contact of relay 25, right-handarmature and back contact of relay 26, lower armature and front contactof relay 27, and winding of relay 31 to grounded battery. Relay 26 isconnected to the contact of relay 31 but it will not operate until relay20 has attracted its armature after the sending of the second impulsedue to its being shunted at the normal contacts of relay 20. hen relay31 is operated and relay 20 attracts its armature at the end of thesecond interruption of the line loop, relay 26 operates over a circuitextending from grounded battery, winding and contacts of relay 31,winding of relay 26, inner right-hand normal contacts of relay 21, andfront contact and upper armature of relay 25 to ground. Relays 31 and 26are locked up over this circuit.

WVhen the impulses have been sent, relay 20 remains energized andslow-to-release re lay 28 deenergizes due to the opening of the holdingcircuit therefor at the contacts of relay 20. Relay 28 in releasingopens the circuit for relay 27. lVhen relay 28 releases a circuit forline signal 32 is completed, said circuit extending from groundedbattery, winding of line signal 32, front contact and left-hand armatureof relay 26, back contact and lower armature of relay 28, back contactand right-hand armature of relay 29, inner right-hand normal contact ofrelay 21, and front contact and upper armature of relay 25 to ground.

The operator noting the line signal may actuate either the lowercontacts of key 23 or the upper or lower contacts of key 22 and then alistening key in a corresponding row to place her telephone set inoperative relaltttl tllllll l.

tion with the calling line. Assuming that the attendant actuates thelower contacts of key 23, the circuit for line relay 20 and supervisoryrelay 24 will be opened, whereupon slow-to-release relay 25 retracts itsarmatures, thereby opening the circuit for busy signal 30 and causingthe release of relays 31, 26 and the deenergization of line signal 32.Supervisory relay 24 is again operated, however, over a circuitextending from grounded battery, left-hand winding of retardation coil6, inner right-hand normal contacts of keys 59 and 39, lower innerright-hand alternate contacts of key 23, winding of supervisory relay24, upper right-hand normal contacts of key 23, through the substationloop, upper left-hand normal contacts of key 23, lower left-handalternate contacts of key 23, inner left-hand normal contacts of keys 39and 59 and righthand winding of retardation coil 6 to ground. Afterinquiring the number desired by the calling subscriber the operator willrestore the listening key to normal.

Assuming that a line having conductors 1 and 2 leading to anothersubstation (not shown) of the private branch exchange is desired bysubstation A, the operator may actuate the upper set of contacts of key-13 to project ringing current from a source of current 5 over theconductors 1 and 2 to signal the substation in the well-known inanner.After ringing, the upper set of contacts will be restored to normal andthe lower contacts of key 43 will be actuated to connect the calling andcalled substations for conversation. Battery supply for the substationsis fed through retardation coil 6.

Upon completion of conversation and res toration of the receivers to theswitchhook of either or both of the calling and called subscriberslines, a circuit including the back contacts of the supervisory relay 2%or 414- and their associated connecting keys will be completed forsupervisory signal 33, which in actuating indicates to the operator thatconversation is completed. The operator may then restore keys 23 and 13to normal, whereupon the calling and called lines are ready for the nextcall.

If the subscriber of station A desires a direct connection with thecentral oiiice, he would, after removing the receiver from theswitchhook, dial digit 3. Line relay 20, supervisory relay 241-,slow-to-release relay 25 and line busy signal 30 would operate inresponse to the removal of the receiver from the switchhook asheretofore described. Relay 28 will operate in response to the sendingof the first impulse and relays 31 and 26 in response to the sending ofthe second impulse over circuits previously traced. Re lays 28 and 27will not release at the end of the second impulse, however, and the'linesignal 32 will therefore not be actuated, but the third interruption ofthe line circuit will release relay 20 thereby completing a circuit forrelay 29 extending from ground, armature and back contact of relay 20,lower armature and front contact of relay 25, right-hand armature andfront contact of relay 26, upper armature and front contact of relay 27,winding of relay 29, back contact and armature of relay 100 to groundedbattery. Relay 29 in operating locks up through its right-hand lternatecontacts and the inner right-hand normal contacts of relay 21 to groundat the upper contact of relay 25. Relay 29 in operating extends groundfrom the upper armature and front contact of relay 25 through the innerrighthand normal contacts of relay 21, front con tact and innerleft-hand armature of relay 29 to the armature and back contact of relay101, which is common to the trunks leading to the central oiiice andthence over conductor, 94:, armature and back contact of relay 60, ifthe trunk D with which this relay is associated is idle, and winding ofallotter relay 61 to grounded battery. Relay 61 in operating completes acircuit for line linde-r relay 62, said circuit extending from ground,upper armature and front contact of relay 25, enter right-hand normalcontact of relay 21, front contact and outer left-hand armature of relay29, conductor 90, upper intermediate armature and front contact of relay61, and winding of relay 62 to grounded battery. Relay 62 in operatingcauses the operation of relays 21 and 60 and extends the calling linethrough to relays 64-. The circuit for the energization of relays 21 and60 may be traced from grounded battery, winding of relay 21, conductor St, front contact and inner left-hand armature of relay 62, and windingof relay 60 to ground. When the calling line is extended through torelay 66%, this relay operates over a. circuit extending from groundedbattery, left-hand winding of relay 64:, back contact and outer lowerarmature of relay 65, intermediate left-hand armature and front contactof relay 62, winding of supervisory relay 24, upper right-hand normalcontacts of key 23 through the substation loop, upper left-hand normalcontacts of key front contact and outer left-hand armature of relay 62,inner lower armature and back contact of relay 65, and right-handwinding of relay 64 to ground. When relay 60 operated, a circuit wascompleted at its right-hand contacts for the energization of trunk busysignal 67. At the left-hand normal contact of relay 60 the starter wirecircuit to relay 61 was opened whereupon relay 101 will be operated toprevent this trunk from being selected. The circuit for the energizationof relay 101 may be traced from grounded battery, winding, front contactand inner lower armature of relay 61, conductor 92, winding of relay101, inner left-hand armature and front contact of relay 29, and frontcontact and upper armature of relay 25 to ground. Relay 21 in operating,at its left-hand contacts, opens the circuit for line relay 20 and atits inner right-hand normal contacts, opens the holding circuit forrelay 29. Relay 29, and in turn relay 101 and the other operated relaysof line A, thereupon release their armatures. The slow to release relay25 is maintained energized when relay 20 re leases however, over acircuit extending from ground, armature and front contact of supervisoryrelay 24, conductor 82, and the winding of relay 25 to grounded battery,relay 24 having been energized when the call.- ing line was extendedthrough to relay 64:. hen relay 29 releases, relay 61 of the trunkcircuit is maintained energized over a circuit extending from ground,upper armature and front contact of relay 25, inner right-hand alternatecontact of relay 21, conductor 88, outer right-hand armature and frontcontact of relay 62, outer and inner lower contacts of relay 61, andwinding of relay 61 to grounded battery. Relay 6 1, in operating,connects ground at its right-hand contacts to conductor 102 of the trunkD leading to the central office, to energize line relay 105 thereat, ifthe trunk circuit terminates in a jack at a manual exchange as shown inFig. 3 or to energize line relay 120 of a nonnumerical switch, if thetrunk circuit terminates in a non-numerical switch F at an automaticexchange as shown in Fig. a. Relay 64: in operating, through itsleft-hand contacts, bridges relay 66 across the trunk conductors 102 and1023. Assuming that the trunk line D is extended to a manual exchange,current for the energization of line relay 105 at the manual exchangewill flow over a circuit extending from grounded batte-ry, winding ofrelay 105, tip contact of jack 107, conductor 102, back contact andupper outer armature of relay 65, and front contact and righthandarmature of relay 6-1 to ground as soon as relay 64L operates. Relay 105in operating completes a circuit for line signal 106.

The operator noting this signal may insert answering plug 108 of a cordcircuit G, a portion only of which is shown, into jack 107 therebydisconnecting line relay 105 from the jack and extinguishin the linesignal 106. Relay 66 of the trunk circuit will be energized over acircuit extending from grounded battery, upper left-hand winding ofrepeating coil 109, upper normal contacts of ringing key 110, tips ofplug 108 and ack 107, conductor 102, winding of relay 66, front contactand left-hand armature of relay 64, conductor 103, rings of jack 107 andplug 108, lower normal contacts of key 110, winding of supervisory relay112 and lower left-hand winding of repeating coil 109 to battery. Relay66 in operating, completes a circuit at its left-hand contact for relay65 which in operating, locks up over circuit extending from groundedbattery, winding and upper inner contact of relay 65, outer right-handarmature and front contact of relay 62, conductor 83, inner right-handalternate contact of relay 21 and front contact and upper armature ofrelay 25 to ground. Relay 65 in operating, extends the calling linethrough to the trunk conductors 102 and 103 and supervisory relay 24: ismaintained operated over a circuit extending from grounded battery,upper left-hand winding of repeating coil 109, upper normal contacts ofkey 110, tips of plug 108 and jack 107, conductor 102, lower inneralternate contacts of relay 65, outer left-hand armature and frontcontact of relay 62, upper lefthand normal contacts of key 23 throughthe substation loop, upper right-hand normal contacts of key 23, windingof supervisory relay 24, front contact and inter mediate left-handarmature of relay 62, lower outer alternate contact of relay 65,conductor 103, rings of jack 107 and plug 108, lower normal contacts ofkey 110, winding of supervisory relay 112 and lower lefthand winding ofrepeating coil 109 to battery. l Vhen relay 65 operates, relays 66 and64 are removed from bridged relationship with the trunk.

The operator at the manual exchange may then actuate listening key 111and inquire the wants of the calling subscriber and after having beeninformed of the number desired, complete the connection over the otherend of the cord circuit (not shown) in the well known manner. Uponcompletion of conversation and restoration of the receiver to theswitchhook at substation A, supervisory relay 24 at the private branchexchange and supervisory relay 112 at the main exchange, will bedeprived of current and will, therefore, retract their armatures. Relay24 in releasing opens the holding circuit for slow-to-release relay 25,which in turn restores all operated relays and busy signal 67 at theprivate branch exchange to normal. The operator at the private branchexchange noting that the trunk busy signal 67 is no longer actuated,will know that the trunk circuit is no longer in use. Supervisory relay112 at the main central oflice, may control the usual supervisorysignals (not shown) and the operator thereat may remove plug 108 fromjack 107 when conversation is completed.

Referring to that part of the description in which it is stated that iftrunk D is idle relay 61 is operated, it will be readily seen that iftrunk D is busy, the starter wire 9 1 will be extended to relay 70, andrelay 71 will be operated. In such case the relays of trunk E willoperate in a similar manner to those of trunk D and the calling linewill be extended over trunk E to the central office. On incoming callsover a trunk such as D to the private branch exchange, line signal 68may be actuated by a source of ringing current projected over theconductors 102 and 103, the path therefore being from conductor 102through the back contact and outer upper armature of relay 65, condenser69 and signal 68 to conductor 103. The operator noting-the signal, mayafter removing the receiver 3 from the switchhook 4 actuate a listeningkey such as to bridge the trunk or the upper set of contacts of key 59thereby bridging holding coil 58 across the trunk, which will actuatethe supervisory signal at the main central oflice in the case ofincoming call from a manual exchange, or trip the ringing relay of anautomatic switch in the case of an incoming call from an automaticexchange. The operator may after actuating her listening key inquire thewants of the calling subscriber. Actuation of the upper set of contactsof key 59 completes a circuit for relay 60 over a path extending fromgrounded battery, resistance 14, upper outer right-hand contacts of key59, and winding of relay 60 to ground. Relay 60 in operating completes acircuit at its righthand contacts for trunk busy signal 67 and itsleft-hand alternate contact extends the starter wire to the next trunk.Assuming that the subscriber of station A is desired, the operator maythen actuate the upper set of contacts of key 23 to project ringingcurrent from a source 5 over the conductors leading to station A tosignal said station. The operator will then restore the upper set ofcontacts of key 23 to normal and operate the lower set of contacts ofkey 23. As soon as the called subscriber responds, supervisory relay 2%which is in series with retardation coil 6 will operate and supervisorysignal 33 will be deenergized, thereby notifyin the operator of theresponse of the called subscriber. The operator may then restore theupper set of contacts of key 59 to normal and actuate the lower set ofcontacts of key 59 which disconnects the local battery supply throughretardation coil 6 and connects subscriber A through to the trunkconductors 102 and 103 over a path extending from conductor 102, lowerleft-hand alternate contacts of key 59, left-hand normal contacts of key39, lower left-hand alternate contacts of key 23, upper left-hand normalcontacts of key 23, through the substation loop, upper right-hand normalcontacts of key 23, through the winding of relay 24, inner right-handalternate contacts of key 23, lower right-hand normal contacts of key39, lower right-hand alternate contacts of key 59 to conductor 103.Battery supply for substation A is obtained from the central oliice. Theactuation of a holding key on an incoming call from the central oflicemay be dispensed with, if the operator actuates a connecting key such asthe lower set of con tacts of key 59, and then the listening key of thecorresponding row of keys, such as 55, and remains in on the connectionuntil the called subscriber responds.

Upon completion of conversation and restoration of the receiver ofsubstation A to the switchhook, supervisory relay 24: will be deprivedof current and will, therefore, release its armature and complete acircuit for supervisory signal 33, thus indicating to the operator atthe private branch exchange that conversation is completed. The operatorat the private branch exchange will thereupon restore keys 23 and 59 tonolrimal and the system is ready for the next ca A more detaileddescription of the operation of the circuit when used in connection withan automatic exchange is not given since such operation will be readilyapparent to those skilled in the art.

If all trunks are busy when a subscriber calls, relays 60 and 7 0 willbe operated and the starter wire 94 will be extended through theleft-hand contacts of relays 60 and 70 over conductor 93 to relay 100.Relay 100 will operate and open the circuit for relay 29 causing relay29 to release. Relay 29 in releasing opens the holding circuit for relay28, line signal 32 will thereupon be actuated over the circuitpreviously traced. The operator on responding thereto may inform thecalling subscriber that all trunks are busy.

What is claimed is:

1. In a telephone exchange system, a call- 1ng line, an impulse sendertherefor, an attendants position, a line signal thereat individual tosaid subscribers line, a trunk circuit, and means responsive to oneseries of impulses from said impulse sender for actuating said linesignal, and to another series of impulses to connect said line to saidtrunk circuit.

2. In a telephone exchange system, a calling line, an impulse sendertherefor, an operators position, a line signal thereat individual tosaid subscribers line, a trunk circuit, and means individual to saidline responsive to one series of impulses from said impulse sender foractuating said line signal and to another series of impulses from saidimpulse sender for connecting said line to said trunk circuit.

3. In a telephone exchange system, a calling line, an impulse. sendertherefor, an operators position, a line signal thereat for saidsubscribers line, a plurality of trunk circuits, means for preselectingsaid trunk circuits, and means responsive to the initiation of a calland the sending of one series of impulses from said impulse sender toactuate said line signal, and to another series of impulses from saidimpulse sender for connecting said line to a preselected trunk.

4. In a telephone exchange system, a calling line, an impulse sendertherefor, an operators position, a line signal thereat for saidsubscribers line, a plurality of trunk circuits, means for preselectingidle trunks, and means individual to said calling line, responsive tothe initiation of a call, and the sending of one series of impulses fromsaid impulse sender to actuate said line signal and to another series ofimpulses from said impulse for connecting said line to a preselectedtrunk circuit.

5. In a telephone exchange system, a calling and a called subscribersline terminating at a first exchange, a trunk line extending from saidfirst to a second exchange, an operators position at said firstexchange, a line signal thereat individual to said calling subscribersline, manual means thereat for interconnecting said lines, a dial foreach of said subscribers lines, a set of relays individual to each ofsaid subscribers lines, responsive to a predetermined series of impulsestransmitted by said dial for actuating the line signal at the operatorsposition and responsive to another predetermined series of impulsestransmited by said dial for automatically extending said line to saidtrunk line.

6. In a telephone exchange system, a subscribers line, an attendantsposition, a line signal thereat individual to said line, a trunkcircuit, means for sending impulses over the two sides of said line inseries, and means responsive to one series of impulses over said line toactuate said signal and to another series of impulses to connect saidline to said trunk circuit.

7 In a telephone exchange system, a calling subscribers line, anattendants position, a line signal individual to said line, a trunkcircuit, an impulse sender for sending impulses over the two sides ofsaid line in series, and relay means responsive to one series ofimpulses over said line to actuate said signal and to another series ofimpulses to connect said line to said trunk circuit.

8. In a telephone exchange system, a first exchange, a second exchange,a plurality of trunk lines extending between said exchanges, a pluralityof subscribers lines at said first exchange, a line signal at said firstexchange for each of said lines, an impulse sender for each of saidlines, means responsive to a certain predetermined series of impulsesfor actuating the line signal of the calling line,-means responsive toanother predetermined series of impulses for extending the calling lineto an idle trunk circuit, and means operative if all trunks are busy tolight the signal of the calling line.

9. In a telephone exchange system, a subscribers line, an attendantsposition, a line signal for said line, a trunk circuit, an impulsesender for sending impulses over the two sides of said line in series,means responsive to one series of impulses over said line to actuatesaid signal, means responsive to another series of impulses over saidline to connect said line to said trunk circuit, and means operative ifall of the trunk circuits are busy to light the signal of the callingline.

In witness whereof, I hereunto subscribe my name this 14th day of JuneA. D., 1920.

SAMUEL B. WILLIAMS, JR.

/ DISCLAIMER.

1;,550,99T:IS[L7)LU6Z B. 'l Vz'lliams, jia, Brooklyn, N. Y.TLLEPHONE-EXCHANGE SYS- =1 assignce, W estem Eledtmc Uompany,Incorporated.

Hereby enters this disclaimer to the said claims of said Letters Patentwhich are in the following Words to Wit:

1. In a telephone exchange system, a calling, line, an impulse sendertherefor, an attendants position, a line signal thereat individual tosaid subscribers line, a trunk circuit, and means responsive to oneseries of impulses fromsaid impulse sender for actuating said linesignal, and to another series of impulses to connect said line to saidtrunk circuit.

2. In a telephone exchange system, acalling line, an impulse sendertherefor,

an operators position, a line signal thereat, individual to saidsubscribers line, a trunk circuit, and means individual to said lineresponsive to one series of impulses from said impulse sender foractuating said line signal and to anotherseries of impulses from saidimpulse sender for connecting said line to said trunk circuit.

6. In. a telephone exchange system, a. subscribers line, an attendantsposition, a. line signal thereat individual to said line, a trunkcircuit, means for sending impulses over the two sides of said line inseries, and means responsive to one series of impulses over said line toactuate said signal and to another series of impulses to connect saidline to said trunk circuit. Y

7. In a telephone exchange system, a calling subscribers line, anattendants position, a line signal individual to said line, a trunkcircuit, an impulse sender 'rmr. Patent dated'Au ust 25, 1925.Disclaimer filed May 24, 1928, by the for sending impulses over the twosides of said line in series, and relay means responsive to one seriesof impulses over said line to actuate said signal and to another seriesof impulses to connect said hne to said trunk circuit.

[Oyficial Gazette J2me 5, 1.928.]

